package leetcode.dynamic;

/**
 * @Description: https://leetcode.cn/problems/climbing-stairs/
 * @Author Ammar
 * @Create 2023/8/3 12:17
 */
public class _70_爬楼梯 {

    public int climbStairs(int n) {
        if (n == 1) return 1;
        if (n == 2) return 2;
        int[] dp = new int[n + 1];
        dp[1] = 1;
        dp[2] = 2;
        for(int i = 3; i <= n; i++) {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        return dp[n];
    }


    public int climbStairs1(int n) {
        int p = 0, q = 0, r = 1;
        for (int i = 1; i <= n; ++i) {
            p = q;
            q = r;
            r = p + q;
        }
        return r;
    }
}
